What You Need to Know About Mesothelioma

Mesothelioma is a form of cancer for which there is a readily identifiable cause: asbestos.

The Environmental Protection Agency (EPA) banned asbestos in 1989. However, it was widely used in the 1950s, 60s and 70s, primarily for insulation on floors, ceilings, water pipes, and heating ducts. Men over age 60 are most likely to develop mesothelioma because of workplace or industrial exposure to asbestos.

Asbestos is a naturally occurring mineral that produces microscopic particles, which can lodge in the lining of the chest cavity. Experts estimate that 1 in 20 workers exposed to asbestos develop mesothelioma—although it can take up to 40 years from initial asbestos exposure to a mesothelioma diagnosis.

What Is Mesothelioma?

Malignant mesothelioma is the most serious of the asbestos-related diseases. These cancers affect the membranes lining the lungs (pleural mesothelioma), abdomen (peritoneal mesothelioma), and heart (pericardial mesothelioma). About three-quarters of mesotheliomas affect the lung membranes.

It's rare: only about 2,500 to 3,000 people in the U.S. are diagnosed annually. But, it's difficult to diagnose. The symptoms—chest pain, chronic coughing, fluid in the chest, and the presence of blood in lung fluid—mimic other common respiratory conditions.

Although industrial asbestos exposure is responsible for about 70 percent of mesotheliomas, natural geological formations called ophiolites also contain asbestos. When human activity or weathering release asbestos fibers in ophiolites, people living nearby (the countries along the Mediterranean and the state of California, for example) may have a higher risk for cancer. Ionizing radiation may also cause mesothelioma, particularly in patients who received radiation to the chest to treat lymphoma and breast, lung, or other cancers.

Can Mesothelioma Be Cured?

The prognosis for mesothelioma is generally not good. Standard treatment—surgery, chemotherapy, radiation—is used for all types, but the most localized cancers are typically not curative. The National Cancer Institute says it's not clear if the overall survival rate of mesothelioma patients improves significantly with different types of treatment, or by a combination of therapies. For example, adding radiation or chemotherapy following surgery does not seem to improve survival rates. Although some combination chemotherapy regimens produced higher response rates in small, early stage clinical trials, they also had toxic side effects.

On a more positive note, the incidence of mesothelioma has probably already peaked in this country due to restrictions on asbestos use. However, experts expect the number of cases to rise internationally.